1. Field of the Invention
The present invention relates to sliding rail assemblies and more particularly, to a ball bushing positioning structure of a sliding rail assembly for server, which uses a release hook to stop a ball bushing in a carrier rail positively in position and allows the ball bushing to be moved with a sliding rail upon insertion of the sliding rail into the carrier rail.
2. Description of the Related Art
Conventional two-stage or three-stage sliding rail assemblies for drawer commonly uses a ball bushing to smoothen sliding movement between two rails. When inserting one first rail, for example, a sliding rail, into a second rail, for example, carrier rail, after a maintenance or repair work, the sliding rail must be kept in alignment with the carrier rail accurately so that the sliding rail can be coupled to the ball bushing. To avoid impact damage of the ball bushing during insertion of the sliding rail, a ball bushing positioning design is necessary. FIGS. 1 and 2 illustrate a ball bushing positioning structure according to the prior art, which was invented by the present inventor. As illustrated, the carrier rail 7 comprises a guide block 71 having a hooked portion 711; the carrier rail 7 defines a slot 72. When the ball bushing 8 is moved with the sliding rail (not shown) out of the carrier rail, the front end 81 of the ball bushing 8 will force downward the hooked portion 711 into the slot 72 of the carrier rail 7, allowing the front end 81 of the ball bushing 8 to move over the hooked portion 711. After the front end 81 of the ball bushing 8 passes over the hooked portion 711, the hooked portion 711 will be engaged into a locating hole 82 of the ball bushing 8 to lock the ball bushing 8 to the carrier rail 7 (see FIG. 2). However, because the server is heavy and its weight can reach 20 kgs, the sliding rail may impact the ball bushing 8 if it is not kept in perfect alignment with the carrier rail 7 during its insertion into the ball bushing 8, and the server may fall with the sliding rail out of the carrier rail 7 during installation.